Adaptive homo-backstepping tracking control for strict-feedback systems in presence of unknown dead-zones

摘要

An adaptive homo-backstepping control for nonlinear strict-feedback systems subjected to unknown actuator dead-zone and disturbance is investigated. A sliding-mode-based integral filter is constructed and used to approximate the desired feedback control in the backstepping-like recursive design technique. Subsequently, the problem of "explosion of complexity" is solved by obviating the analytic derivatives deduction for virtual control in the conventional backstepping technology. The actuator dead-zone dynamic is modeled as the combination of a line and a disturbance-like term, which makes the controller design simpler. The interconnected control module and filter module in the resulting closed-loop system satisfy the input-to-state practically stability-modularity condition, provided that the small-gain theorem is exploited to ensure the stability of closed-loop system. The proposed approach cannot only mitigate the effect of dead-zone but also solve the problem of explosion of complexity in the previous literature. Numerical simulations performed on a manipulator with a brushed DC motor are introduced to illustrate the effectiveness of underlying control scheme.